Procalcitonin versus C-reactive protein for predicting pneumonia in adults with lower respiratory tract infection in primary care

Anette Holm, Svend S Pedersen, Joergen Nexoe, Niels Obel, Lars P Nielsen, Ole Koldkjaer, Court Pedersen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

BACKGROUND: The role of procalcitonin in diagnosing bacterial infection has mainly been studied in patients with severe infections. There is no study on the value of procalcitonin measurements in adults with lower respiratory tract infection (LRTI) treated in primary care. AIM: To evaluate the accuracy of plasma procalcitonin in predicting radiographic pneumonia, bacterial infection, and adverse outcome in a population of adults with LRTI treated in primary care. DESIGN OF STUDY: Prospective, observational study. SETTING: Forty-two general practices and an outpatient clinic at the Department of Infectious Diseases, Odense University Hospital, Denmark. METHOD: A total of 364 patients with LRTI were prospectively enrolled from 42 general practices. Patients were examined with chest radiography, microbiological analyses, and measurements of C-reactive protein (CRP) and procalcitonin. The outcome measure was hospitalisation within 4 weeks of enrollment. RESULTS: Median procalcitonin was 0.05 ng/ml, which was below the functional sensitivity of the assay (0.06 ng/ml). In predicting radiographic pneumonia, bacterial infection, and hospitalisation, the sensitivities of procalcitonin >0.06 ng/ml were 0.70, 0.51, and 0.67, and of CRP were > or =20 mg/l, 0.73, 0.56, and 0.74 respectively. Corresponding positive predictive values were between 0.09 and 0.28. CONCLUSION: Both procalcitonin >0.06 ng/ml and CRP > or =20 mg/l were associated with radiographic pneumonia, bacterial infection, and subsequent hospitalisation, but positive predictive values were too low for any of the two inflammatory markers to be of use in clinical practice. To measure procalcitonin values accurately in the primary care setting, a more sensitive method is needed, but there was no indication that procalcitonin is superior to CRP in identifying patients with pneumonia, bacterial aetiology, or adverse outcome.
Original languageEnglish
JournalBritish Journal of General Practice
Volume57
Issue number540
Pages (from-to)555-560
Number of pages5
ISSN0960-1643
Publication statusPublished - 1. Jul 2007

Keywords

  • Adolescent
  • Adult
  • Aged
  • Biological Markers
  • C-Reactive Protein
  • Calcitonin
  • Denmark
  • Family Practice
  • Humans
  • Middle Aged
  • Pneumonia, Bacterial
  • Pneumonia, Viral
  • Predictive Value of Tests
  • Prospective Studies
  • Protein Precursors
  • Sensitivity and Specificity

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